As the year moves towards the festive season the issue of legal highs, or new psychoactive substances (NPS) as they are technically known, is back under the spotlight.
Campaigners say the open sale of legal highs has led many young people to experiment with with experimental drugs whose effects are dangerous and unknown.
The National Federation of Retail Newsagents (NFRN) released a briefing note in November formally warning its members of the consequences of supplying these substances to customers.
Meanwhile the government announced in the Queen's Speech in May that it was introducing the Psychoactive Substances Bill to ban the production, distribution, sale and supply of all legal highs from 2016.
However this move has already been criticised by MPs and some of the government's own drug advisors as too broad and difficult to enforce.

What are legal highs?
The term legal highs is somewhat misleading as it only means a chemical for sale that is not yet covered under Misuse of Drugs Act 1971. Sellers technically operate under trading standards legislation, not criminal law.
Despite legal highs containing one or more chemical substances which produce similar effects to illegal drugs like cocaine, cannabis and ecstasy, they are therefore not illegal to use and possess unless they are later banned.
Over the last ten to fifteen years many legal highs have emerged.  Well known examples include the cannabis substitute Spice and Mephedrone, a stimulant that mimicked the effects of  amphetamines.
Mephedrone has since been banned but has gone on to become a popular street drug.
Technically retailers cannot knowingly sell any unbanned legal high if they believe a customer will consume it. Therefore these products are often packaged as incense, salts, plant food, or labelled 'not for human consumption' to get round the law.
The legal highs trade has flourished through high street outlets popularly known as 'head shops', specialist websites and through some independent corner stores and market stalls.
The legal highs industry is frequently supplied by labs in China who routinely send mislabelled chemicals to the UK using courier services. The internet allows buyers in the UK to communicate easily with the manufacturers in East Asia who supply them.
According to the NFRN the number of deaths linked from legal highs, including those since made illegal, has risen steadily, from 12 people in 2009 to 97 people in 2012. This figure does not include those cases where users' health has been badly damaged from using legal highs but such cases have included brain damage, fits and heart attacks.
There are simply no rules in the unregulated trade, with lists of ingredients on packaging being meaningless until products can be tests in a laboratory.
Even then there is often not enough actual research about the substances sold to know their potency, the likely effects from consumption, or what reaction use with other substances such as alcohol will have on a person.
As a result as soon as a new drug is identified, the Home Office issues a temporary ban on the substance, before investigations about whether to ban it permanently under the Misuse of Drugs Act are carried out.
More than 500 such drugs have been banned by the government since 2010 but the process is so time-consuming that the BBC reports the official published list of banned substances hasn't been updated since 2012.
Many substances which are banned don't even appear in official legislation and sellers may not even be aware that illegal drugs are now being sold from their premises.
Moreover suppliers often just design new variates after a previous form has been banned. The new Psychoactive Substances Bill is intended to settle both of these issues.

A changing legal situation
The problem of legal highs is not a devolved policy area so London makes the policy for the whole of the UK on this issue.
At present no one piece of criminal legislation entirely covers legal highs. But many retailers and other sellers have been charged with criminal and civil offences related to their sale ever since legal highs began to enter the UK drugs market fifteen years ago.
For example local councils in Scotland have begun implementing 'NPS forfeiture orders' to confiscate stocks of legal highs from high street stores. Edinburgh council has recently been leading the way after being granted forfeiture orders from the Sheriff Court which cover a large number of brand names and chemical substances. The council's powers can be also extended to cover any legal high for sale in Edinburgh.
But the government has rejected this approach and moved to dismantle the legal highs industry in its entirety through the new bill.
However its new proposed blanket ban on psychoactive substances would be highly unusual in British law, as it brings in a complete ban on every psychoactive substance and then introduces a list of exemptions for those already in everyday use, such as alcohol and coffee.
In late October this proposed legislation was criticised by the Home Affairs Select Committee, chaired by Keith Vaz MP, which released the report of an enquiry it had held into the upcoming legislation around legal highs.
The MPs were already concerned that the government had broken a promise by rushing the bill into its parliamentary stages before they could complete their evaluation. They had wanted an impact assessment on similar legislation in Ireland to be undertaken before it became law.
But the committee had other criticisms to make, including saying there was lack of clarity on the different amounts of harm caused by different types of legal highs. It recommended that appropriate sentences and guidelines should be requested from the Sentencing Council.
The committee gave examples, recommending that Nitrous Oxide – known as "laughing gas" – should be reviewed by the Council to consider whether it should be controlled under the existing drug laws given the growth in its use.
It added that the party drug "poppers" should not be banned, saying its misuse was not enough to make it a social problem at present.
The MPs conceded that legislation on the legal highs problem was needed. But they argued that the bill's definition of legal highs was too broad and didn't define what a psychoactive substance actually was very well.
This left it open to legal challenges from retailers, drugs companies and church groups, who have all raised concerns about the unintended consequences of the bill on their work.
The Home Secretary's own expert drug advisers at the Advisory Council on the Misuse of Drugs (ACMD) have also criticised the bill, saying it risks "serious unintended consequences".
They pointed out that directors of many premises and venues could be left liable for prosecution for legal highs used on their properties even though many are undetectable by drug dogs and urine tests.
The ACMD also warned the new law risked handing out seven-year prison sentences to the sellers of benign or even helpful herbal medicines, and criminalised young people for 'social dealing', the practice of clubbing together to buy drugs with friends.

Legal highs and retailers
Meanwhile the independent retail sector itself has long warned retailers against the sale of legal highs through convenience store outlets.
The NFRN made its position abundantly clear when NFRN National President Ralph Patel personally warned its members that: "Although marketed as 'legal' substances, this doesn't mean that legal highs are safe for people to use. I cannot make it any clearer than this, you should categorically not sell them."
But senior figures in the industry also share some of the worries expressed by the ACMD and the Home Affairs Select Committee about the weaknesses of the Psychoactive Substances Bill.
The Head of Communications & Research at ACS, Chris Noice, pointed out that: "Retailers may come across products that look inconspicuous and are labelled as not for human consumption, but are known to users as legal highs."
This would still leave them liable for prosecution under the bill if it were to become law.
But even if the Psychoactive Substances Bill does pass, few expect the trade in legal highs to end with the closing of legal loopholes that allowed them to be sold without prosecution under the Misuse of Drugs Act.
With the closure of head shops where the substances are easy to find, the trade is likely to shift to the same criminal networks that sell illegal drugs on the streets or move to online websites on the so-called 'darknet' which have succeeded the notorious Silk Road as drug buying platforms.
ACS chief executive James Lowman spoke for many retailers when he commented: "We believe that the banning of legal highs is a positive step, but these products must be clearly defined and retailers provided with comprehensive guidance so that they do not accidentally fall foul of the regulations."